This Month's Other Crucial Privacy Debate: The Rocky Future of Arrestee DNA Collection

Last week, the Supreme Court ruled 5-4 that Maryland has the right to collect DNA evidence from people arrested for — though not yet convicted of — a serious crime. The ruling is poised to have broad legal implications, since 28 states have a similar law that permits DNA collection upon arrest. It should also spark a broad social debate, weighing matters of civil liberties and privacy against public safety and forensic science.

There's no straight path forward here, so I'm going to breakdown the three main arguments for, against, and qualifying the decision.

First some background. The case centered on a man named Alonzo King who was charged in 2009 with assault for brandishing a shotgun. A DNA sample swabbed from him at booking turned up a database match for an unsolved rape from 2003. King was convicted of the rape, but Maryland's Court of Appeals overturned the low court, calling the cotton swab an unlawful search. The new Supreme Court judgment reversed the Court of Appeals.

The case divided America's highest court along rather unusual lines. Justice Scalia, a reliable conservative, sided with Justices Ginsberg, Sotomayor, and Kagan, reliable liberals, in the minority. The majority opinion, written by Justice Kennedy, called DNA swabbing of arrestees a "reasonable search" under the Fourth Amendment and compared the process to taking fingerprints. Scalia's lively dissent flays that opinion, fearing a slippery slope to more personal violations [PDF]:

Make no mistake about it: As an entirely predictable consequence of today’s decision, your DNA can be taken and entered into a national DNA database if you are ever arrested, rightly or wrongly, and for whatever reason.

Three Arguments For Routine Arrestee DNA Collection

1. The principle argument for taking arrestee DNA (though not the one made by the Supreme Court majority) is that doing so increases the chances of solving serious crimes. The technique seems especially promising for old rapes and murders that have gone cold. Authorities in Kansas, for instance, reported nearly 300 hits to offender profiles in 2011, with roughly half of those coming courtesy of DNA collected from arrestees.

2. Only the most hard-nosed Fourth Amendment advocate could see DNA collection as an invasive search. The procedure involves a quick cheek wipe, known as a "buccal swab," that takes little time and requires negligible intrusion; additionally, the sequence kept on file reveals minimal personal information. There are far worse violations of personal space occurring at airport security lines every day.

3. Like it or not, policing in cities is already going the way of broad surveillance. That trend has been clear in places like New York for years and will likely expand in the wake of the Boston Marathon bombings. The widespread use of security cameras in public spaces has a lot in common with arrestee DNA swabs: both must be done responsibly lest they encroach too far on the privacy of innocent people, but also leverage modern data technology to serve the broader good.

Three Arguments AgainstRoutine Arrestee DNA Swabbing

1. The effectiveness of collecting DNA from arrestees lacks clear empirical support. For starters, many of the crimes resolved with the help of the DNA database would be resolved even if laws limited DNA collection to convicted criminals. Beyond that, as Brandon Garrett and Erin Murphy pointed out in Slate before the Supreme Court ruling, the best studies suggest that collecting DNA from crime scenes is much more useful than collecting it from offenders.

2. Expanding the DNA database from convicted criminals to mere potential criminals opens the door toward universal collection. As Scalia writes in his dissent, surely society would catch more criminals if everyone's DNA were collected when they got a driver's license — but then what type of free society would we be preserving? Moreover, the risk for false accusation presumably rises with the expansion of the DNA database, too.

3. Minorities will bear the brunt of the procedure. As Richard Lempert writes for Brookings, African Americans will have a disproportionate likelihood of being linked to a crime through the DNA database simply because they're arrested (and thus will be swabbed) more often. Beyond that, he writes, since DNA strands can also implicate family members, the suspect net will be cast to a broad minority population "who have never done anything to justify having their DNA typed."

1. States vary considerably (and dangerously) in their definition of the law. While some states only collect DNA from people arrested for felonies or repeat offenders, others collect on misdemeanors and one collects from any illegal immigrant. Worse yet, while profiles are supposed to be expunged if a case is dismissed or a suspect acquitted, the individual must initiate this process in 18 states — an offensive stipulation that must be amended.

2. Arrestee DNA collection costs a lot of money and takes a lot of time. States requiring this additional booking step are burdening localities with the need for additional laboratory equipment, loads of administrative staff, and several levels of training. Arrestee profiles now make up about 10 percent of the national database, meaning the resources required for this step will only increase and must be taken into consideration by policymakers.

3. Profile classifications should be updated at every step of the legal process. Without this real-time database, it's often hard to know whether it was the DNA collected upon arrest (legally debatable) or upon conviction (legally accepted) that led to the criminal match. In two states with clear records, the Urban Institute did find that arrestee DNA profiles aided criminal investigations; on the whole, however, states must do a better job classifying DNA so we know just how effective arrestee laws really are.

About the Author

Eric Jaffe is a senior associate editor at CityLab. He writes about transportation as well as behavior, crime, and history, and has a general interest in the science of city life. He's the author of A Curious Madness (2014) and The King's Best Highway (2010), and lives in New York.